RI-cisternographyと気脳写脳表像が逆の陰影を呈した小児片麻痺の2症例—Paradoxical phenomenaか

PARADOXICAL PHENOMENON IN FLOW OF THE AIR AND RADIOISOTOPE OVER THE HEMISPHERIC CONVEXITIES IN HEMICONVULSION-HEMI-PLEGIA-EPILEPSY SYNDROME:REPORT OF TWO CASES

I．はじめに

　Radio isotope cisternography （以下RI-Cistと略す）が1953年に発明され，Di-Chiroにより臨床面に活用されるようになつた^3〜6）。RI-Cistの特徴は髄液の流れを可視的にとらえることにあり，主にnormal pressurehydrocephalusをはじめとする外科的疾患の判定に応用されてきた^{2,10,12,14,17,18）}。私達も小児の脳障害における髄液動態をしる一助として，本法を実施しているが，最近Hemiconvulsion Hemiplegia Epilepsia SyndromeのRI-Cistにおいて気脳写の脳表への空気陰影像と，一見相反する現象を呈する2症例を経験したので報告する。

Cisternography has been utilized to differentiate the various form of hydrocephalus, to detect and quantify CSF fistula, to evaluate CSF diversienary shunts for patency, and to detect and characterize abnormal communications with the CSF space. The pattern of radiopharmaceutical movement as a re-flection of CSF flow and distribution have been discribed and the relation of this diagnostic method to pneumoencephalogram has been discussed.

In a course of evaluation with PEG and RI-cisternography for metal retardation of children. paradoxical manifestations in flow of the air and isotope over the hemispheric convexities have been observed. In two cases with hemiconvuluion-hemi-plegia-epilepsy syndrome (HHE), where hemiatrophy of the brain was marked, the subarachnoid space over the more affected convexities was filled by the air, while the space over the opposite convexity was well demonstrated. They were girls and the ages at the examination were eight years and twelven years respectively. Simple skull X-ray showed that the aflected side of the calvaria was thickened and the petrous ridge was higher than the other side. Cerebral angiography revealed hemiatrophy of the affected side, but neither vas-cular malformation, tumor nor subdural effusion.

When¹⁶⁹Yb was injected into the lumber sub-arachnoid space, on the more affected hemisphere it reached the frontal pole and the Sylvian area in 1 h. At 3 hours the radionuclide was abserved overthe convexity of the more affected hemisphere, with increased uptake. The 24 hour image demon-strated continuous high activity over the affected hemisphere. Besides, a delay of disappearance of the isotope was observed even after sixteen days. On the other hand, the activity was sparse over the opposite hemisphere throughout the examination.

If the ventricles are considerably enlarged, there may be an associated entry of radio-activity into the ventricles. Then the increased subarachnoid space may be reflected by the delayed movement of injected radio-pharmaceutical through the sub-arachnoid spaces. In our cases, however, entry of the radiopharmaceutical into the lateral ventricles was not demonstrated.

These cases are different from the asymmetrical convexity flow on the scan, which can be secondary to degenerative disease, traumatic encephalopathy, CNS inflection, etc., to puddling in some areas and lack of filling in others. These combinations of images can also be caused when one hemisphere is atrophic and the other hemisphere obstructed. This was illustrated by a case of arteriovenous malfor-mation of the brain following hemorrhage. The atrophy with puddling overlies the malformation, while the hemorrhage has caused obstruction of the remaining subarachnoid spaces. Cause of the dis-crepancy between flow of the air and isotope ob-served in the present cases was unclear.